CN109085541B

CN109085541B - MIMO radar array antenna and signal processing method thereof

Info

Publication number: CN109085541B
Application number: CN201811047679.4A
Authority: CN
Inventors: 问翔
Original assignee: Hangzhou Eagleguard Technology Co ltd
Current assignee: Hangzhou Eagleguard Technology Co ltd
Priority date: 2018-09-07
Filing date: 2018-09-07
Publication date: 2021-02-02
Anticipated expiration: 2038-09-07
Also published as: CN109085541A

Abstract

The invention provides an MIMO radar array antenna and a signal processing method thereof, relating to the technical field of radar, wherein the MIMO radar array antenna comprises: two transmitting antennas and four receiving antennas; the four receiving antennas are sequentially arranged at a preset first interval, one transmitting antenna is arranged on the outer side of the first receiving antenna, and the other transmitting antenna is arranged on the outer side of the fourth receiving antenna; the transmitting antenna and the adjacent receiving antenna are away from each other by a preset second interval; and the preset second interval is larger than half of the working wavelength of the MIMO radar array antenna. The invention can better restrain leakage signals.

Description

MIMO radar array antenna and signal processing method thereof

Technical Field

The invention relates to the technical field of radars, in particular to an MIMO radar array antenna and a signal processing method thereof.

Background

The radar is a radio device which actively transmits electromagnetic waves and receives target reflected waves to actively detect and locate a target. Radar systems that detect targets primarily on ground vehicles, personnel and low-altitude aircraft have a requirement to detect targets at close range and to effectively suppress the effects of ground objects on ground clutter generated by radar returns. The radar system adopting the MIMO system (hereinafter referred to as MIMO radar) can transmit orthogonal signals, in-phase addition of the signals cannot be formed at a transmitting end, and compared with the radar system of the traditional paraboloid and flat plate form antenna, the MIMO radar has stronger clutter interference resistance.

In the prior art, for the MIMO detection radar for the short-range ground target, X and Ku wave bands are mostly adopted, and the MIMO antenna generally adopts a mode that the interval between a transmitting antenna and a receiving antenna closest to the transmitting antenna is half of the working wavelength of the system, so that the isolation degree is low. For example, the transmit-receive isolation can only be about 30dB, it is difficult to suppress the transmission signal (leakage signal for short) leaking into the front end of the receiver, and excessive leakage signal will have adverse effect on the normal operation of the radar system.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a MIMO radar array antenna and a signal processing method thereof, which can suppress a leakage signal well.

In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:

in a first aspect, an embodiment of the present invention provides a MIMO radar array antenna, including: two transmitting antennas and four receiving antennas; the four receiving antennas are sequentially arranged at a preset first interval, one transmitting antenna is arranged on the outer side of the first receiving antenna, and the other transmitting antenna is arranged on the outer side of the fourth receiving antenna; the transmitting antenna and the adjacent receiving antenna are away from each other by a preset second interval; and the preset second interval is larger than half of the working wavelength of the MIMO radar array antenna.

With reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, where the preset second interval is greater than an operating wavelength of the MIMO radar array antenna.

With reference to the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, where the preset second interval is greater than the preset first interval.

With reference to the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, where an isolator is further disposed between the transmitting antenna and the adjacent receiving antenna.

With reference to the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, where a mixer is further connected after each receiving antenna.

With reference to the first aspect or one of the fourth possible implementation manners of the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where the MIMO radar array antenna operates in a C-band.

In a second aspect, an embodiment of the present invention further provides a signal processing method for a MIMO radar array antenna, where the method is applied to the MIMO radar array as in any one of the first aspects, and the method includes: selecting a signal to be transmitted; the signal to be transmitted is two phase-orthogonal linear frequency modulation signals; preprocessing a signal to be transmitted, wherein the preprocessing comprises matched filtering processing and/or Dechirp processing; transmitting the preprocessed signals to be transmitted outwards through two transmitting antennas, and respectively receiving echo signals reflected by the target through four receiving antennas; each receiving antenna corresponds to a virtual receiving channel; separating the received signal of each receiving antenna into two channel signals with orthogonal phases so that the four receiving antennas form eight channel signals; processing the eight channel signals in the distance dimension and the Doppler dimension in sequence to obtain signal data corresponding to the eight channel signals so as to determine angle information of the target based on the signal data; wherein the data processing includes operations including FFT processing, non-coherent accumulation, and CFAR processing.

With reference to the second aspect, an embodiment of the present invention provides a first possible implementation manner of the second aspect, where the step of determining angle information of the target based on the signal data includes: and determining the angle information of the target by adopting a least square method or a classical spectrum estimation algorithm based on the signal data.

With reference to the second aspect, the present invention provides a second possible implementation manner of the second aspect, wherein the two phase-orthogonal chirp signals are a first chirp signal and a second chirp signal, respectively; the first chirp signal and the second chirp signal each include two sub-periods; the phases of the first linear frequency modulation signal in the two sub-periods are 0 and 0 respectively; the second chirp signal has a phase of 0 and pi in the two sub-periods, respectively.

In combination with the second possible implementation manner of the second aspect, the embodiment of the present invention provides a third possible implementation manner of the second aspect, wherein a bandwidth of each sub-period is 30MHz, and a central frequency range of each sub-period is between 5.5GHz and 5.7 GHz; the frequency modulation period of each sub-period is 250 mus.

The embodiment of the invention provides an MIMO radar array antenna, which comprises two transmitting antennas and four receiving antennas; the four receiving antennas are sequentially arranged at a preset first interval, one transmitting antenna is arranged on the outer side of the first receiving antenna, and the other transmitting antenna is arranged on the outer side of the fourth receiving antenna; the transmitting antenna and the adjacent receiving antenna are away from each other by a preset second interval; and the preset second interval is larger than half of the working wavelength of the MIMO radar array antenna. The distance between the transmitting antenna and the receiving antenna of the MIMO radar array antenna provided by the embodiment of the invention is more than half of the working wavelength, so that the isolation is effectively improved, and the inhibition capability of a leakage signal is increased.

In addition, the embodiment of the invention provides a signal processing method for the MIMO radar array antenna, which can select and process a signal to be transmitted, and then perform signal separation, FFT processing, non-coherent accumulation, CFAR processing and the like on the received signal to obtain signal data, so as to determine angle information of a target based on the signal data. The method is more suitable for the MIMO radar array antenna provided by the embodiment of the invention, and the signal processing method is helpful for the MIMO radar array antenna to perform target detection more accurately.

Additional features and advantages of embodiments of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention as set forth above.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a MIMO radar array antenna provided by an embodiment of the present invention;

fig. 2 is a schematic diagram of another MIMO radar array antenna provided by an embodiment of the present invention;

fig. 3 is a flow chart of a signal processing method according to an embodiment of the present invention;

fig. 4 is a schematic diagram illustrating a signal processing method according to an embodiment of the present invention;

fig. 5 shows a schematic diagram of a wave path difference provided by the embodiment of the invention.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

At present, the radar system applied to short-range detection mostly adopts a continuous wave system in order to avoid introducing unnecessary range detection blind areas into pulse signals. The large energy transmit signal from the transmit antenna leaks directly to the receive antenna and enters the receiver. The larger power will cause the active device of the receiver to be saturated and not work, and in a serious case, the active device of the receiver can be even burnt. In order to suppress the leakage signal, one solution is: a transmitting antenna and a receiving antenna are respectively adopted, and an isolation measure is adopted between the transmitting antenna and the receiving antenna to reduce leakage signals entering a receiver. For the antenna of the radar system in the C-band, to achieve a larger isolation, a distance between the transmitting antenna and the receiving antenna (hereinafter referred to as a transceiving distance) needs to be larger, but once the transceiving distance exceeds half of the operating wavelength of the system, a rear-end angle measurement algorithm of the radar system cannot directly use a traditional angle measurement method such as a spectrum estimation algorithm. Therefore, the distance between the transmitting antenna and the receiving antenna (hereinafter referred to as a transceiving distance) of the existing radar system is short, for example, only one half wavelength of the closest transceiving interval is adopted at most, so that the isolation is low, the transceiving isolation is only about 30dB, and the transmission signal leaked to the front end of the receiver is difficult to be inhibited.

Based on this, the MIMO radar array antenna and the signal processing method thereof provided by the embodiments of the present invention can be applied to various fields requiring radar detection, such as the radar technical field and the ground security technical field, and the MIMO radar array antenna provided by the embodiments of the present invention mainly includes two transmitting antennas and four receiving antennas (i.e., 2 transmitting and 4 receiving), can form coverage (± 45 °) to a 90 ° range in the azimuth, and simultaneously, adopts the MIMO system, can form virtual receiving of 8 channels, thereby effectively increasing the accuracy of angle measurement. In the MIMO radar array antenna provided by the embodiment of the present invention, the distance between the transmitting antenna and the receiving antenna closest thereto exceeds half of the operating wavelength of the system, and isolation between transmitting and receiving is further increased. The following describes embodiments of the present invention in detail.

First, referring to a schematic diagram of an MIMO radar array antenna shown in fig. 1, the MIMO radar array antenna is shown to include two transmitting antennas and four receiving antennas; the four receiving antennas are sequentially arranged at a preset first interval, one transmitting antenna is arranged on the outer side of the first receiving antenna, and the other transmitting antenna is arranged on the outer side of the fourth receiving antenna; the transmitting antenna and the adjacent receiving antenna are away from each other by a preset second interval; and the preset second interval is larger than half of the working wavelength of the MIMO radar array antenna. In fig. 1, the preset first interval is represented by d, and the preset second interval is represented by the minimum transceiving interval.

The distance between the transmitting antenna and the receiving antenna of the MIMO radar array antenna provided by the embodiment of the invention is more than half of the working wavelength, so that the isolation is effectively improved, and the inhibition capability of a leakage signal is increased.

In order to further improve the isolation, the transceiving distance can be increased, and a sufficient space can be left between the receiving antenna and the transmitting antenna to place a device for increasing the isolation. That is, the distance between the receiving antenna and the transmitting antenna exceeds twice the half wavelength, so that an isolator is provided between the transmitting antenna and the adjacent receiving antenna. For ease of understanding, reference may be made to another MIMO radar array antenna schematic shown in fig. 2, where fig. 2 is a schematic diagram of an isolator shown on the basis of fig. 1.

It can be understood that the MIMO radar array with 2 transmitters and 4 receivers provided in this embodiment can form 8 virtual channels, and a conventional radar array may be respectively connected with 2 mixers after each receiving antenna, and a total of 8 mixers are required, and each mixer forms a channel signal after each mixer so as to form 8 channel signals. However, this approach obviously increases the complexity and cost of the radar system, so that the radar system provided in this embodiment is only connected with one mixer after each receiving antenna, and then is processed by software implementation manners such as signal separation on the basis of the hardware, and this approach can effectively reduce the complexity and cost of the radar system.

In specific implementation, the MIMO radar array antenna provided by this embodiment operates in the C-band.

On the basis of the MIMO radar array antenna, the present embodiment provides a signal processing method for a MIMO radar array antenna, referring to a flow chart of the signal processing method shown in fig. 3, where the method includes:

step S302, selecting a signal to be transmitted; the signals to be transmitted are two phase-orthogonal linear frequency modulation signals.

For example, the two phase-orthogonal chirp signals are a first chirp signal and a second chirp signal, respectively; the first chirp signal and the second chirp signal each include two sub-periods; the phases of the first linear frequency modulation signal in the two sub-periods are 0 and 0 respectively; the second chirp signal has a phase of 0 and pi in the two sub-periods, respectively.

In one embodiment, the bandwidth of each sub-period is 30MHz, and the center frequency of each sub-period ranges from 5.5GHz to 5.7 GHz; the frequency modulation period of each sub-period is 250 us.

Step S304, preprocessing the signal to be transmitted, where the preprocessing includes matched filtering and/or Dechirp (frequency hopping removal).

Step S306, transmitting the preprocessed signals to be transmitted outwards through two transmitting antennas, and respectively receiving echo signals reflected by the target through four receiving antennas; each receiving antenna corresponds to one virtual receiving channel.

Step S308, the received signal of each receiving antenna is separated into two channel signals with orthogonal phases, so that the four receiving antennas form eight channel signals. The received signal is also the echo signal reflected by the target and received by the receiving antenna.

Step S310, carrying out data processing on the eight channel signals in the distance dimension and the Doppler dimension in sequence to obtain signal data corresponding to the eight channel signals so as to determine angle information of a target based on the signal data; the data processing includes FFT (Fast Fourier transform) processing, non-coherent accumulation, and CFAR (Constant False Alarm Rate) processing. When the angle information of the target is determined based on the signal data, the angle information of the target may be determined based on the signal data by using a least square method or a classical spectrum estimation algorithm.

The signal processing method provided by the embodiment of the invention can select and process the signal to be transmitted, and then perform signal separation, FFT processing, non-coherent accumulation, CFAR processing and the like on the received signal to obtain signal data, so as to determine the angle information of the target based on the signal data. The method is more suitable for the MIMO radar array antenna provided by the embodiment of the invention, and the signal processing method is helpful for the MIMO radar array antenna to perform target detection more accurately.

For the sake of understanding, the following description of the signal processing method with reference to a schematic diagram of the signal processing method shown in fig. 4 specifically explains the following:

the selection of the signal to be transmitted may be target dependent, such as 2 chirp signals with signal parameters of 250 mus for efficient detection of a moving body within a preset range (such as 400 m). The center frequency of the linear frequency modulation signal is variable within the range of 5.5 GHz-5.7 GHz, the signal bandwidth can be 30MHz, and the distance resolution can be 5 meters. In practical application, the two transmitted signals can be orthogonal by adopting a phase coding mode. The phases of the transmission signal of the transmission antenna 1 in the two sub-periods are 0 and 0, and the phases of the transmission signal of the transmission antenna 2 in the two sub-periods are 0 and pi, respectively. In this way, the separation of the two echo signals can be obtained at the receiving end by adding and subtracting the two sub-periodic signals. In particular, one processing cycle may be completed for 512 periodic signals, i.e., 1024 sub-periodic signals. For example, the velocity measurement range is 0.3m/s to 30 m/s. The sub-period signal with a discrete sampling rate of 250 mus has 4096 samples, i.e. 4096 points of data of one sub-period of 4 channels are input as shown in fig. 4.

When processing a linear frequency modulation signal, there are two methods, namely, matched filtering and Dechirp (Dechirp) processing. The matched filtering process is to perform FFT on the signal, multiply the signal by a filter coefficient of a corresponding signal form, and perform IFFT (Inverse Fast Fourier Transform) on the signal to obtain a waveform in which the echo amplitude is distributed along the distance. The matched filtering process is typically performed in the digital domain, i.e. after AD (analog-to-digital) conversion of the signal. The Dechirp processing is to mix the received echo signal and the conjugate of the transmitted signal at the radio frequency end of the antenna, convert the distance of the target relative to the radar into different frequencies from the time relationship, and then use an ADC (Analog-to-Digital Converter) and perform FFT to obtain the curve of the target echo amplitude in the distance. The radar system in the MIMO mode needs to separate echoes of different transmitted signals before processing. It is conventional practice to mix different transmit signals with the receive signal at the mixer end of the radio frequency and then to obtain separation of the different signals by filtering. Corresponding to the MIMO system with 2-transmitting and 4-receiving proposed in the embodiment of the present invention, the conventional method is to connect two mixers after each receiving antenna, and perform mixing processing with 2 transmitting signals respectively. Each of the 4 receiving antennas is connected to 2 mixers, so that 8 mixers are required, and 8 channel signals are required to be formed after the mixers, however, the conventional method increases the complexity and cost of the system. Based on this, the embodiment of the present invention uses two chirp signals whose phases are orthogonal to each other as the transmission signal. The first sub-period signals of the two transmitting signals are the same, and the phase difference of the second sub-period is 180 degrees. After the AD sampling, the signals are added and subtracted, that is, the 4-channel 4096 point data shown in fig. 4 is added and subtracted in the first sub-period and the second sub-period, and the two transmission channel signals are separated to form 8 channels, so that only 4 reception channels are needed in the radio frequency band, and the system complexity and cost are greatly reduced. As shown in fig. 4, after performing FFT processing on 4096 point data, the embodiment of the present invention further extracts the first 200 point data to perform distance dimension non-coherent accumulation and CFAR for 8 channels and 512 cycles, and performs doppler dimension FFT processing on the detected distance signals at 512 points in 8 channels and performs doppler dimension CFAR.

Specifically, when signals are accumulated and detected, in order to effectively reduce the computation amount and simultaneously not reduce the detection performance of the radar system, non-coherent accumulation and CFAR processing are firstly carried out on a distance dimension, a distance unit signal with a higher amplitude on the distance is extracted, and then CFAR processing with a lower accumulation and false alarm rate is carried out along a Doppler dimension, so that the system cost and the computation amount are reduced. The radar system firstly carries out FFT processing on each channel signal to obtain a curve of the echo amplitude of each channel along the distance distribution. In consideration of the phase difference caused by the distance difference between different channels, the present embodiment employs non-coherent accumulation, where 512 periodic signals of 8 channels in one processing period are subjected to non-coherent accumulation, and then CFAR processing is used to perform first threshold detection on a target. Because there is a loss of the snr in the non-coherent accumulation mode, the false alarm rate corresponding to the first threshold may be set slightly larger. On the basis of distance-dimensional non-coherent accumulation and distance-dimensional CFAR processing, 512-point FFT processing can be performed on detected distance unit signals corresponding to 8 virtual channels, 8-channel non-coherent accumulation and Doppler-dimensional CFAR processing can be performed, second threshold detection is performed on a target, and then angle information is extracted by adopting an angle measurement algorithm based on 8-channel signal distance-Doppler points. In the embodiment of the invention, only 8 channels of non-coherent accumulation are needed, 512-point FFT is equivalent to coherent accumulation of 512 frequency modulation periods, and the false alarm rate corresponding to the detection threshold can be set to be very small.

The embodiment of the invention also provides an angle measurement algorithm, which is specifically explained as follows:

after receiving the signal, the radar system processes the signal and needs to judge the angle of the target. Referring first to fig. 5, a schematic diagram of the wave path difference is shown, specifically illustrating the wave path difference formed by the geometric relationship between the transmitting antenna, the receiving antenna and the target angle,

assume that the distance between the transmitting antenna 1 and the transmitting antenna 2 is L and the spacing between the receiving antennas is d. Then for the transmit signal of the transmit antenna 1, assuming that the target is at an angle θ from the normal, there are path differences dsin θ, 2dsin θ and 3dsin θ for the receive antennas 2, 3 and 4, respectively, with respect to the receive antenna 1. The phase difference introduced by the wave path difference is dsin theta/lambda, 2dsin theta/lambda and 3dsin theta/lambda. For the signal transmitted by the transmitting antenna 2, the path difference is lssin θ, (L + d) sin θ, (L +2d) sin θ and (L +3d) sin θ with respect to the signal of the transmitting antenna 2 received by the receiving antenna 1. The introduced phase difference is Lsin theta/lambda, (L + d) sin theta/lambda, (L +2d) sin theta/lambda and (L +3d) sin theta/lambda. When the minimum transceiving distances are d/2, d, 3d/2 and 2d, the receiving antenna 1 is used for receiving the transmission signal of the transmitting antenna 1 as a reference, and the relative phase difference received by each antenna is shown in the following table 1, wherein the table 1 shows that the different transmitting antenna distances are the phase differences (multiplied by 2 pi) which are used for receiving the signal of the transmitting antenna 1 by the receiving antenna 1 as the reference

Table 1.

In the first case, where the transmit-receive antenna spacing is d/2, the phase difference between the virtual channels that can be formed is fixed, so the angle estimation can be performed directly using the least squares method, MUSIC method, or other modern spectral estimation algorithms. And when the distance between the transmitting and receiving antennas is increased to d, 3d/2 and 2d from d/2, the phase difference between the 5 th channel and the 4 th channel is no longer d sin theta/lambda but 2d sin theta/lambda, 3d sin theta/lambda and 4d sin theta/lambda. When d is λ/2, the phase difference of the 5 th channel signal relative to the 4 th channel signal at different transmitting antenna intervals can be calculated to be 2 pi sin θ, 3 pi sin θ and 4 pi sin θ. If no blurring is to occur, it is required to have | sin θ | ≦ 1, | sin θ | ≦ 2/3, and | sin θ | ≦ 1/2, respectively, i.e., it is required that the target angle distribution from the front surface cannot be greater than ± 90 °, ± 41.8103 °, and ± 30 °. It can be seen that if an angle measurement algorithm is also used at this time with a minimum separation d/2 from the transmit receive antenna, errors will be introduced due to ambiguity in the phase difference between the 5 th and 4 th channels. To solve this problem, the present embodiment adopts two methods. The first mode is as follows: and (3) subtracting the phase of the previous channel from the phase of each channel by adopting a least square method from the channel 2, and removing the phase of the channel 5 minus the phase of the channel 4 to obtain 6 equation calculation target angles. The second method is as follows: the 1 st to 4 th channel signals, namely the signals of the receiving and transmitting antenna 1, and the 5 th to 8 th channel signals, namely the signals of the receiving and transmitting antenna 2, are respectively used for estimating angles by a classical spectrum estimation algorithm and then averaged. The two methods can better solve the contradiction between the requirement of the antenna isolation and the angle measurement ambiguity.

In summary, the MIMO radar array antenna and the signal processing method thereof provided in this embodiment may have the following beneficial effects:

(1) the interval between the transmitting antenna and the receiving antenna is increased, so that the isolation between the transmitting antenna and the receiving antenna of the MIMO radar system is effectively increased, the signal energy leaked from the transmitting signal to the receiving end is reduced, and the inhibiting capability of the leaked signal is enhanced.

(2) Each receiving antenna is only connected with 1 mixer, then signal processing is carried out through software implementation modes such as signal separation, and the problem of angle ambiguity caused by the increase of the space of the MIMO transmitting antenna is solved by adopting a method of abandoning one channel signal.

(3) The number of signal channels of the radio frequency part of the front-end receiver can be effectively reduced. According to the traditional MIMO radar, 8 receiving channels need to be obtained at the beginning of receiver mixing, and the scheme provided by the embodiment of the invention effectively enables the number of the channels at the front end of the receiver to be consistent with the number of MIMO receiving antennas, thereby reducing the complexity of the system.

(4) The method for respectively performing CFAR processing on the distance dimension and the Doppler dimension is adopted, and under the condition of ensuring the detection rate, the two-dimensional processing method that the traditional method performs FFT on all distance units is avoided, so that the calculation amount of the system can be effectively reduced, and the cost of the system is further reduced.

In contrast, the conventional MIMO radar adopts a mode of separating transmitting and receiving antennas, that is, no matter how many transmitting antennas are, a transmitting antenna array is located at one side of the antennas, a receiving antenna is located at the other side of the antennas, and isolation measures are adopted between the transmitting and receiving arrays. By the method, the antenna array surface is larger, and the cost of antenna development and production is increased. The front end of the receiver starts from the mixer, the number of the receiving channels which is the product of the transmitting antenna and the receiving antenna of the MIMO system is adopted, the number of the channels of the receiver is large, and the complexity and the cost of the system are high. The signal processing adopts two-dimensional FFT, and FFT is directly carried out on the distance unit, but the operation amount is large, so that the MIMO radar provided by the embodiment of the invention has remarkable progress compared with the existing MIMO radar.

The MIMO radar array antenna and the computer program product of the signal processing method thereof provided by the embodiments of the present invention include a computer readable storage medium storing a program code, where instructions included in the program code may be used to execute the method described in the foregoing method embodiments, and specific implementation may refer to the method embodiments, and will not be described herein again.

In addition, in the description of the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A MIMO radar array antenna, comprising: two transmitting antennas and four receiving antennas;

the four receiving antennas are sequentially arranged at a preset first interval, one transmitting antenna is arranged on the outer side of the first receiving antenna, and the other transmitting antenna is arranged on the outer side of the fourth receiving antenna;

the transmitting antenna is away from the adjacent receiving antenna by a preset second interval; the preset second interval is larger than half of the working wavelength of the MIMO radar array antenna;

or the preset second interval is greater than the working wavelength of the MIMO radar array antenna;

the preset second interval is greater than the preset first interval.

2. The MIMO radar array antenna of claim 1, wherein an isolator is further disposed between the transmitting antenna and the adjacent receiving antenna.

3. The MIMO radar array antenna of claim 1, wherein a mixer is connected after each of the receive antennas.

4. The MIMO radar array antenna of any one of claims 1 to 3, wherein the MIMO radar array antenna operates in the C-band.

5. A signal processing method for a MIMO radar array antenna, the method being applied to the MIMO radar array antenna according to any one of claims 1 to 4, the method comprising:

selecting a signal to be transmitted; the signal to be transmitted is two phase-orthogonal linear frequency modulation signals;

preprocessing the signal to be transmitted, wherein the preprocessing comprises matched filtering processing and/or Dechirp processing;

the preprocessed signal to be transmitted is transmitted outwards through the two transmitting antennas, and echo signals reflected by a target are respectively received through the four receiving antennas; each receiving antenna corresponds to a virtual receiving channel;

separating a receiving signal of each receiving antenna into two channel signals which are orthogonal in phase, so that the four receiving antennas form eight channel signals;

processing the eight channel signals in the distance dimension and the Doppler dimension sequentially to obtain signal data corresponding to the eight channel signals, and determining the angle information of the target based on the signal data; wherein the data processing includes operations including FFT processing, non-coherent accumulation, and CFAR processing.

6. The method of claim 5, wherein the step of determining the angular information of the target based on the signal data comprises:

and determining the angle information of the target by adopting a least square method or a classical spectrum estimation algorithm based on the signal data.

7. The method of claim 5, wherein the two phase-quadrature chirp signals are a first chirp signal and a second chirp signal, respectively; the first linear frequency modulation signal and the second linear frequency modulation signal respectively comprise two sub-periods;

wherein the phases of the first chirp signal in the two sub-periods are 0 and 0, respectively;

the phases of the second linear frequency modulation signal in the two sub-periods are respectively 0 and pi.

8. The method of claim 7, wherein the bandwidth of each of the sub-periods is 30MHz, and the center frequency of each of the sub-periods ranges from 5.5GHz to 5.7 GHz; the frequency modulation period of each sub-period is 250 mus.